1. Field of the Invention
The present invention relates to a memory device, in particular, to a DRAM (dynamic random access memory) used as a main memory in a computer or the like.
This application is based on Patent Application No. Hei 10-365556 filed in Japan, the contents of which are incorporated herein by reference.
2. Description of the Related Art
In consideration of the manufacturing costs and so on, DRAMs are generally used as the main memory of a computer or the like. In the operation of continuously reading or writing internal data of the DRAM, a command used for such a continuous operation is set in advance in the DRAM, a line address is selected, and then column addresses are selected. In order to continuously read or write the data of the next line, a similar operation is necessary, that is, the address signal of the next line must be selected, and then the addresses of the relevant columns must be selected.
In addition, a dedicated memory device in which the above-explained continuous reading/writing operation is possible is known; however, in such a device, the speed of reading or writing data is important and thus the random access function is impossible. That is, in the conventional memory device, the random access function and the continuous reading/writing function (of the line and column addresses) are incompatible.
As described above, in the operation of continuously reading or writing internal data in the DRAM, a command assigned to such a continuous operation is set in advance in the DRAM, a line address is selected, and then column addresses are selected, thereby starting the continuous reading or writing operation.
If it is assumed that line address A is selected, after the data of the last column in the designated line of address A is read or written, the data of the first column of the next line of address A+1 is continuously read or written. At this line shift, it is also necessary to select the next-line address A+1 and the relevant column address, that is, the time for selecting the above line address A+1 and the column address is necessary, so that it is very difficult to further improve the data reading/writing speed.